1. Field of the Invention
The present invention relates to an anti-androgenic agent, and more particularly to an agent for inhibiting the binding of 5.alpha.-dihydrotestosterone (hereinafter referred to as "5.alpha.-DHT") with androgen receptor, and a process for obtaining the same.
2. Related Arts
Anti-androgenic medicines have been administered for preventing or curing androgen dependent diseases, for instance, hypertrichosis, acne, male pattern alopecia, prostatomegaly, prostatic tumor, male precocity and the like. In general, the medicines comprise a compound having a steroid skeleton as an effective ingredient, and thus the administration thereof has been limited in dose to prevent side effects.
Referring now to the activity of an anti-androgenic substance, anti-androgenic action means an action for decreasing the androgenic activity of testosterone, and is caused by an inhibition of binding of 5.alpha.-DHT with androgen receptor, or inhibition of the 5.alpha.-reductase activity which reduces testosterone into 5.alpha.-DHT.
Recently, it has been reported in Jap. Pat. No. 60-146829 (A) that an extract obtained from various herbs shows the latter anti-androgenic action, namely a certain inhibition of the activity of 5.alpha.-reductase. The present inventors have also found that an extract of Swertia japonica Makino shows such inhibition and that the compound showing the inhibition is oleanolic acid as one of oleanane type triterpene compounds, and reported the same in Jap. Pat. No. 60-126218 (A). Among said two anti-androgenic actions, it has been considered that the former action, namely, the inhibition of binding of 5 .alpha.-DHT with androgen receptor is more effective than the latter, but there is no report whether an extract of herbs shows such inhibition of binding or not.